[当我在Python3.7上运行下拉列表程序时，Kivy立即崩溃

Question

我在使用kivy时遇到了一些问题[[更多。每当我运行以下程序时，python都会立即崩溃，打开的窗口将变为空白，我别无选择，只能关闭它。试图修复此问题大约一个小时，但似乎无法完成任何事情。

而且，我在追溯中也没有错误。

感谢您的帮助

from kivy.uix.dropdown import DropDown
from kivy.uix.button import Button
from kivy.uix.floatlayout import FloatLayout
from kivy.app import App
from os import listdir


class CustomDropDown(DropDown):
    def __init__(self,**kwargs):
        self.layout = FloatLayout()
        self.fileList = []

    def dropdown(self):
        self.musDir = listdir(r'C://Users//danburnier//Desktop//PythonPrograms','r')
        for file in self.musDir:
            if file.endswith('.py'):
                btn = Button(text=str(file[:-3]),size_hint_y=None,height=44)

                btn.bind(on_release=lambda btn:self.select(btn.text))

                self.add_widget(btn)

class DropDownApp(App):

    def build(self):

        mainButton = Button(text='Touch me.',size_hint=(None,None))
        mainButton.bind(on_release=d.open)
        d.bind(on_select=lambda instance, x: setattr(mainButton, 'text', x))
        return CustomDropDown()

d = CustomDropDown()

if __name__ == '__main__':
    DropDownApp().run()

编辑：
我不知道它是否能帮上忙，但是在Thonny上（在树莓派4上）运行它，我得到以下回溯：
[INFO] [Logger      ] Record log in /home/pi/.kivy/logs/kivy_20-03- 
03_19.txt

[INFO] [Kivy        ] v2.0.0rc1, git-Unknown, 20200303

[INFO] [Kivy        ] Installed at "/home/pi/.local/lib/python3.7/site-
packages/kivy/__init__.py"

[INFO] [Python      ] v3.7.3 (default, Apr  3 2019, 05:39:12) 

[GCC 8.2.0]

[INFO] [Python      ] Interpreter at "/usr/bin/python3"

[INFO] [Factory     ] 184 symbols loaded

[INFO] [ImageLoaderFFPy] Using ffpyplayer 4.3.1

[INFO] [Image       ] Providers: img_tex, img_dds, img_sdl2, img_pil, 
img_ffpyplayer (img_gif ignored)

[INFO] [Window      ] Provider: sdl2

[INFO] [GL          ] Using the "OpenGL" graphics system

[INFO] [GL          ] Backend used <sdl2>

[INFO] [GL          ] OpenGL version <b'2.1 Mesa 19.2.0-rc1'>

[INFO] [GL          ] OpenGL vendor <b'Broadcom'>

[INFO] [GL          ] OpenGL renderer <b'V3D 4.2'>

[INFO] [GL          ] OpenGL parsed version: 2, 1

[INFO] [GL          ] Shading version <b'1.20'>

[INFO] [GL          ] Texture max size <4096>

[INFO] [GL          ] Texture max units <16>

[INFO] [Window      ] auto add sdl2 input provider

[INFO] [Window      ] virtual keyboard not allowed, single mode, not docked

[INFO] [Text        ] Provider: sdl2

Backend terminated or disconnected.Fatal Python error: Segmentation fault

Current thread 0xb6fccad0 (most recent call first):
  File "/home/pi/.local/lib/python3.7/site-packages/kivy/core/window/__init__.py", line 1309 in add_widget
  File "/home/pi/.local/lib/python3.7/site-packages/kivy/app.py", line 927 in _run_prepare
  File "/home/pi/.local/lib/python3.7/site-packages/kivy/app.py", line 949 in run
  File "/home/pi/Desktop/Music21/ProgFin/ScrollMenu22.py", line 34 in <module>
  File "/usr/lib/python3/dist-packages/thonny/backend.py", line 1211 in _execute_prepared_user_code
  File "/usr/lib/python3/dist-packages/thonny/backend.py", line 1139 in wrapper
  File "/usr/lib/python3/dist-packages/thonny/backend.py", line 1152 in wrapper
  File "/usr/lib/python3/dist-packages/thonny/backend.py", line 1198 in execute_source
  File "/usr/lib/python3/dist-packages/thonny/backend.py", line 840 in _execute_source
  File "/usr/lib/python3/dist-packages/thonny/backend.py", line 826 in _execute_file
  File "/usr/lib/python3/dist-packages/thonny/backend.py", line 387 in _cmd_Run
  File "/usr/lib/python3/dist-packages/thonny/backend.py", line 195 in handle_command
  File "/usr/lib/python3/dist-packages/thonny/backend.py", line 137 in mainloop
  File "/usr/lib/python3/dist-packages/thonny/backend_launcher.py", line 76 in <module> Use 'Stop/Restart' to restart ...

Answer 1

嗯，您的代码完全错误且充满错误。首先，应该打开DropDown以显示它。您不打开它。第二，您的CustomDropDown类继承了DropDown。为什么？您不重写任何一种方法，您试图做什么？第三，您在该类中具有函数，但是您没有调用它。它不会自己运行。第四，您没有该类的对象，对d变量中的对象进行了处理，但是随后返回了新的空白对象。如果返回d，它也不会正常工作，但请注意这种情况。您创建了布局，但没有使用它。

也许会按您的意愿工作：

class DropDownTest(FloatLayout):
    def __init__(self, **kwargs):
        super(DropDownTest, self).__init__(**kwargs)

    dropdown = DropDown()
    musDir = listdir(r'C://Users//danburnier//Desktop//PythonPrograms','r')
    for file in musDir:
        if file.endswith('.py'):
            btn = Button(text=str(file[:-3]),size_hint_y=None,height=44)
            btn.bind(on_release=lambda btn: self.dropdown.select(btn.text))
            self.dropdown.add_widget(btn)
    mainbutton = Button(text='Open DropDown', on_release=dropdown.open)
    dropdown.bind(on_select=lambda instance, x: setattr(mainbutton, 'text', x))
    self.add_widget(mainbutton)

class DropDownApp(App):

    def build(self):
        self.ddtest = DropDownTest()
        return self.ddtest

if __name__ == '__main__':
    DropDownApp().run()

您可以在函数中放一些东西，但不要忘记调用它。